LEDs are here

Thursday

Sep 27, 2012 at 9:07 AMSep 27, 2012 at 12:07 PM

They're here.

By Juliet Grable

They're here.

LEDs, or light-emitting diodes, are on the verge of taking over the lighting industry, though you wouldn't necessarily know it by checking out bulb aisles in local hardware stores. There, you're likely to find modest displays of LEDs crowded among halogen, compact fluorescent and traditional incandescent light bulbs.

LED "bulbs," or lamps, look just as strange and space-agey as spiral-shaped compact fluorescents once did. A transparent globe encases a stem clustered with individual LEDs, each about the size of a match head.

LEDs are made by purposely contaminating tiny flakes of semiconducting material with impurities to make them conductive. The movement of charged particles releases energy in the form of light. LEDs produce monochromatic light in every color of the rainbow, which makes them perfect for decorating Christmas trees or creating nightclub ambience. Creating white LEDs has proved trickier because white light includes all colors of the spectrum, but now stores stock "warm white" LED bulbs that screw into traditional bases. Their cost is upward of $8.99.

Stephen Morrow, owner of O'Handy's Handyman Service in Ashland, is ahead of the curve. The self-described "energy freak" bought his first LED bulb nearly three years ago for a fixture above his bathroom sink. Since then he's bought two more; he's also wrapped a ceiling fan with LED "rope" lights.

"I'd rather have LEDs than CFLs," says Morrow. "Especially since I have kids."

Compact fluorescent (CFL) bulbs are fragile and contain mercury. LEDs are made without hazardous materials. They're also small, durable and don't put out much heat, which means less damage to fabric or other materials, including human skin. They light up immediately and fail gradually by growing dimmer over time — a very long time. LEDs enjoy a life expectancy of 25,000 to 50,000 hours. By comparison, a CFL lasts about 12,000 hours, an incandescent a mere 1,000.

But the greatest advantage of LEDs is their extreme efficiency. The U.S. Department of Energy claims LEDs can potentially cut our energy use for lighting by a quarter to half, which is why the agency is investing so much money into research. Today, LEDs are everywhere, illuminating traffic signals, car taillights, streetlights, signs and cellphone displays. Because they're naturally compatible with 12-volt systems, they're also common in RVs and boats.

But developing a high-quality, efficient, white light remains the Holy Grail for manufacturers. The preferred method involves coating blue LEDs with a yellow phosphor material, which converts light into wavelengths that appear white. Although some efficiency is lost during this conversion, bulbs made this way use no more energy than CFLs. But can their light match the candlelike warmth of incandescent bulbs?

Light quality usually is evaluated on two things: the "correlated color temperature" of the light, (measured on the Kelvin scale) and the ability of a light source to accurately render color. We've all been victims of poor color rendering; just imagine the way your skin looks under low-quality fluorescent lights. Most manufacturers include ratings for color appearance and rendering on their packaging. For example, warm, white, interior lighting falls between 2,700 and 3,000 K. But the best way to judge a light's quality is to see for yourself.

At Grover Electric and Plumbing Supply in Medford, a display in the bulb aisle allows customers to compare incandescent, halogen, CFL and LED bulbs side by side. The LED bulb, made by Philips, emits 805 lumens, the equivalent of a 60-watt incandescent, but only uses 12.5 watts. Yellow phosphor the color of egg yolk coats the inside of the globe; however, any resemblance to a bug light ends with the flip of a switch. The bulb casts a warm, white and very bright glow. The downside? It costs $25.